Bladder stiffener



Jui? 31 1945` J. w. OVERBEKE BLADDER STIFFENER Filed April 25, 1944 John WzZZtQm Overefe www Patented` July 31, 1945 John William Oven-beke, New York, N.

to Simmonds Aeroeessories,

Y., aligner Ine. of. New York,

New York, N. Y., a corporation of New York Application April 25. 1944, Serial No. 532.580 8 Claims. (CI. 13S-30) This invention relates to pressure jars or vessels such as accumulatore and surge relievers wherein a iluid is stored lmder pressure and more particularly to such vessels having a novel bladder stiil'ener as'a component part.

General obiects of the invention are to provide pressure vessels of thementioned types having improved reliability and eiiiciency in expelling contained fluid into the service line.

In the pressure accumulator type of vessel. as used on aircraft and elsewhere. there is usually a strong premura shell having an internally disposed membrans or bladder separating the shell into an air and an oil compartment. The hydraulic service line is connected with the oil compartment. and air imder pressure is trapped in the air compartment. In a typical illustrative installation, air may be introduced at a pressure of 800 p. s. i. and cil thereafter pumped into and stored in the accumulator at a pressure of 1500 p. s. i., so that the air volume is correspondingly reduced and the separating bladder nsxed or collapsed to accommodate itself to the new condition. 'I'his 'bladder may either be of a bag-like form attached near one end of the accumulator Shel' or of diaphragm form attached at its edges about medially of the shell which in this case is made sectionally in halves with the diaphragm clamped therebetween.

The ilrst mentioned bag-like form has certain relative advantageasuch as allowance of the use of a strong 'seamless shell, and the avoidance of undue ilexure near the attaching edges, which often leads to early fatigue and tearing of the diaphragm types of membranes. One disadvantage of the bag-like end-attached form of blad der, however. is that it may trap oil between itself and the shell walls. especially in the upper section remote from the oil plus.r if operated when inverted or in some other non-upright attitude. It is desirable, particularly. in aircraft installations, that the accumulator size and weight be kept at the lowest limits commensurate with the volumetric requirements of the hydraulic system, and to this end one of the test requirements for such accumulatore is an emciency of 95% in exvantages of a bag-WDG bladder. wherein provision is made to prevent undue oil trapping.

Further objects of the invention are to provide an accumulator wherein the-bladder is held extended by a separate inner bladder stiirener which serves to hold at least the upper portion -of the bladder outwardly against the shell walls so as to avoid formation of oil trapping pockets and to control and guide the nexing and collapsing action of the membrane.

Additional objects of the invention are to provide a bladder stiffener having advantages such as'those described, which can be separately applied to existing as well as to new accumulator assemblies. and which permits the use of a thin uniformly walled bladder which is easy to cure properly and has a relatively small heat-retainins mass.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction. combination of elements,

and arrangement of parts, which will be exempli ned in the construction hereinafter set forth, and the scope of which invention will be indicated in the claims. i

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Fig. I is a vertical medial sectional view through a pressure accumulator embodying features of the invention.

Fig. 2 is a fragmentary vertical sectional view .showing a modiiled form of bladder stiii'ener peiling contained oil to the system lines in allv attitudes. Trapping or cutting on oi' pockets of oil from access to the oil passage or plug at the end of the accumulator accordingly may, if present in a substantial amount. result in test failure and rejection as well, of course. as in ineilicient operation during use.

More particular objects of the present invention are to provide accumulatore having the adusable in an assembly such as that shown in Fig. 1.

Figs. 3 and 4 are fragmentary views partly in section showing, respectively, additional forms of stiiiening rings usable in the bladder stiifeners of Fig. 1 `or, 2.

Referring more particularly to the drawing and ilrst to the form of device shown in Fig. l, there is shown a pressure accumulator comprising a shell ill having an air back-check valve lil at one end and an oil passing plug i2 at the other. A bladder il is attached within the shell with its interior in communication with the air introducing valve Il in the form shown. It will be understood however that the benefits of the present invention will obtain if the liquid iluid is contained within the bladder and the gaseous iiuid is trapped within the shell outside the bladder. and if desired either of these arrangements may frequidteeluucitmsuenxtaandsbmtywrunction over a wide temperature range. Materials bestnllingalloftheserequirementsareusually arathergummystockanditisimportanttoprotectthexnasfarasposuibleagainsttearingforcesl andagainsttheformationofsharpfoldsand creases as the bladder collames or crumples during operation.

Asshown the bladder il is of bag-like form at- I tached within the shell near one end thereof. In

the illustrated form it is attached to a closure of thegeneraitypeshownandclaimedinmycopending application 8er. No. 515,933, iiied Decemamate bladder. rms, coupled with the msnm-uns action of the bladder .stiifener which holds the upperpart ofthe bladder out toward the msu 'ber 28, 1948. The bladder terminates in beaded attaching edges il which are clamped between a collar I8 andan outwardly slidabie stopper Il which isurged outwardly under interior accumu-l lator pressure into tight sealing vengagement with the bladder neck il. Outward movement of the collar Ilia by a segmented locking ring i1 seated in an annular groove within the shell mouth, while inward dropping of the stopper with respect tothe collar is prevented by va stop nut il and inward dropping movement oi the collar ii with respect to the shell is prevented by a stop ring il to which the collar ispinned.

'l'.'he oil plug i2 may be of any suitable construction and is preferably of the form particularly described and claimed in my co-pending applicatlon Ser. No. 615,984 filed December 28, 1948. The accumulator structure-thus far described is generally of known construction and does not form-part of thel present invention except insofar as it is employed in combination with the novel bladder stifiener about to be described.

This stiifener, .which is 'generally designated Il; comprises a stiening ring 2l which is adapted to urge the bladder into extcndedeposition toward or against the shell walls at a point intermediate the top and bottom of the bladder and preferably at a point approximately midway of the height of the shell in the case of a spherical accumulator of the kind illustrated. An attaching bead or necktlissnappedrseatedinanannularnllet provided therefore on the lower end of the stopper It and asu'pportlng web 2t serves to'suspend the stiifening ring 2| from such attaching integrally thickened up neck. If desired one or more intermediate stiileningringsorbeadsumaybeprovidedaswell as vertically extending stiifening ribsll which, if employed, may be distributedin suitable number. say 6 or 8, about the suspending web'structure.'AsillustratedinPig.-1thestiileningring or rings, the attaching neck and the supporting web are all integrally molded from synthetic rubherlor other suitable stock.which is capable of eollapdng so as'to be insertable through the shellv mouth butwhich is formulated and cured to have sumcient and approach to rigidity to springoutwardly into bag supporting relation when-permittedtodoso.

The main stii'iening ring clably large .diameter'and'a gently curving peu at the lower tei-minal edge of the bladder stiife'ner has an appreripheral contour Il not only to give it the requi- -site stillness a'nd strength but also to guide and vaginates control the bladder as it flexes and in upon itself during operation oi' theaccumulator. Th'sprevents the formation of sharp folds and also guides and controls the ilexing'action of the bladder so as to prevent indiscriminate and uncontrolled collapsingand crumpling walls, serves to avoid the formation'cf pockets and the trapping of oil between the bladder and shell walls where it 'would be cut of! from return lto the pressure system .through the plug il.

Preferably a slight amount of oil may be trim in the space Il. but this is merely to prevent squeezing of the bladder into the lJoint crevices .in and around the stopper and is not present in a desired one or more intermedate stiifening rings ill may be provided. Here the web or supporting means for suspending the stiil'ening rings from the attaching neck are in the form of separate ilexlble strapslil preferably formed of textile material such as canvas or duck which is folded around the attaching neck and stiiiening rings and suitably stitched so as to conne and support the latter. If desired the supporting straps ill may be i'ormed of synthetic rubber, leather or other like material suitably stitched, vulcanized, or cemented in place. In the form shown in Fig. 2 the entire supporting structure comprises `a skeletal framework which is light and which involves little added heat retaining mass. This last characteristic is highly desirable. Heretofore efforts have been made to combat the oil trapping problem by ding bladders with an wall section terminating in some cases with angintegral thickened bead around which the lower portion of the bladder, which is leftl of normally thin dimension is adapted to fold. It is dimcult to vulcanize or cure such a thick and' thin walled bladder structure .properly and with uniformly predictable results,

cycle. It will be seen that with the light skeletal textile framework of Pig. 2 such heat storing problems are largely avoided while yet securing the desired bladder stiifening'and extending ac. tion which serves to prevent oil trapping.

In Fig. .3 'a modiiiedform of stifiening ring is shown which may be incorporated' in or attached to the bladder4 stiifenersof either Fig. 1 or 2.v

Here th'e stiening ring-22| Ihas an interior stiflening coil spring' embedded and molded therein so as to increase the outward expanding bias of the ring.

In Fig. 4 'a' somewhat similar arrangement is `shown involving a stiifening ring inthe form of an outer tube 32| ofjsynthetic rubber or the like within which is inserted a coil stiiiening spring 32|. Other forms of interior s'tiifeners such. as steelbands.whalebone.etc.,maybeembedded 0f the infhsval'illlltieningl'lllllihlicuqftllclpllllll 2.8 or 328. and may be similarly embeddedV in the vertical ribs 25 or straps |23.

It will be seen that there have been provided bladder stifleners which are capable of being applied either to existing o'r to specially formed accumulator shell and bladder assemblies, which may b e of the spherical types shown, or of elongate cylindrical or any other desired form. In this connection it will be lobvious that the particular attaching means such as the bead or neck 22 may be adapted to the requirements of the particular accumulator assembly with which the bladder stiffener is used, the illustrated form of elastic snap ring and grooved stopper being convenient in the particular arrangement illustrated. In general the attaching neck or bead for the bladder stiiener may partake of the same attaching means employed to secure the attaching edges of the bladder itself within the accumulator shell.- It will also be seen that with the present form of bladder stiiIener the bladder may be of normally thin and substantially uniformly walled structure which is easy to cure properly and does not have undesirable heat retaining characteristics, and that in general the described constructions are suited to fuliill their intended functions.

Since certain changes may be made in the vabove construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specic features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A'pressure accumulator comprising, a shell having fluid passages therein, a bladder attached within said shell in communication with one of said passages, and a separate bladder stiiener attached within said bladder and arranged to hold the portion adjacent the attached end of said bladder extended outwardly toward said shell while leaving the remainder thereof relatively free to iiex.

2. A pressure accumulator comprising, a shell having fluid passages therein, a bladder attached within said shell in communication with one of said passages, and a separate bladder stiilener within said bladder and comprising a ring of stiiening material which ring is less collapsible than said bladder tendingto hold itextended against the walls of said shell.

3. A pressure accumulator comprising, a shell having iiuid passages therein, a bladder attached within said shell in communication with one of said passages, and a separate bladder stiiener attached within said bladder comprising a stiiener positioned to extend said bladder intermediate its ends and a supporting web suspending said stiifener from its place of attachment. l

4. A pressure accumulator comprising, a shell having iluid passages therein, a bladder attached within said shell in communication with one of said passages, and a separate bladder stiflenerv attached within said bladder comprising a stiiiener positioned to extend said bladder intermediate its ends and a supporting web suspending said stiffener from its place of attachment, said web being in the form of a plurality oi' spaced straps.

5. A pressure accumulator comprising, a shell having uid passages therein, a bag-like bladder attached within said shell in communication with one of said passages, and a plurality of contractible resilient stiiiening rings within said bladder, said rings being separate from and more resistant to collapse than said bladder and urging it into extended position toward the shell walls.

6. A bladder stiiener for holding an accumulator bag extended, comprising a stiflening ring, an attaching neck adapted to be fitted to the accumulator, and means suspending said ring from said neck.

JOHN WIILIAM OVERBEKE. 

